Great list of questions. Hopefully we can get some answers to these, and I"ll happily collate them into the master.
-blam On Mon, 24 Jan 2005 15:04:24 -0600, Paul Leppert <[EMAIL PROTECTED]> wrote: > Blammo, > > How about questions related to HDTV setup in mythtv? > > - How are HDTV channels set up? Using zap2it and an HDTV lineup > resulted in a mix of NTSC and ATSC channels with incorrect freqid for > the digital channels (e.g., in Chicago, Channel 7 (ABC) is actually > broadcasting on 52). How is this set up via mythtv? > > - How are HDTV subchannels set up? Again, based on above, ABC is > multicasting on 52. In mythtv, are the channels specified as freqid > 52-1, 52-2? or some other format? How should these multi-channels be > set up for names (mythtv channel input won't allow '.' (7.1, 7.2, > etc.) or '-' (7-1, 7-2). Do these channels need to be renumbered > (e.g., 900, 901)? For me, I cannot seem to get any other subchannel > other than the first regardless of what I put in the freqid field in > mythweb (using an HD-3000). > - Based on http://thegeorges.us/mythtv instructions, the mythconverg > database needs to be tweaked to set channel format to ATSC (assuming a > default of NTSC). Is this necessary? What are the correct commands > for setting this up? > - If your mythtv setup receives OTA NTSC and ATSC, is there any reason > to keep the NTSC channels within mythtv? If so, how should these be > set up (similar issues as above since you now have two (or more) > channel 7's)? Is there a priority scheme within mythtv to make sure > it records a show off the ATSC stream before choosing the same show on > the NTSC stream? > - Does transcoding need to be set up in mythtv for HD channels (my > understanding of the HD stream is that it contains all subchannels. > Does mythtv filter out the "extra" subchannels or do you need to use > the transcoding mechanism to reduce the file sizes?) I have no idea > how any of this works in mythtv. > > And questions for performance: > > - What components of the mythtv / computer setup impact performance of > HDTV (e.g., at a given hardware level, what is the CPU usage for > recording? what is it for playback, what is it for both)? > - Related to above, what is the impact of multiple HDTV captures > (e.g., two HD-3000 cards) on the processing requirements of the PC? > Anybody here yet? Anybody have an idea of what it takes > processing-wise for HDTV PIP with two cards? > - What can be done to improve performance (how is resolution reduced? > Is there any impact (or even capability) of recording at lower > resolution than 720p or 1080i/p? Is there an easy way to playback at > different resolutions (via mythtv rather than different modelines). > - If a modeline is set up for a particular monitor at a particular > resolution, does that automatically reduce the processing of an HDTV > stream (in other words, if I'm playing a 720p ATSC stream (1280x720) > back on a monitor at 480p (704x480), have I somehow reduced the > processing impact, or is the mythtv box still handling the full > processing impact and all that is happening is a reduction in quality > on the output)? > - For playback, what is the processing impact for different > resolutions (playing back a 720p stream at 1280 x 720, 1024 x 576, 800 > x 450)? > - For those trying to get the best performance (at the tradeoff of > quality), what is the best way to play back HDTV? Reducing playback > resolution? Transcoding to reduced resolution? etc. etc. > - What about audio? Are there general rules about digital audio and > performance or is this generally "not an issue" based on using a 5.1 > sound card (e.g., SB Audigy)? > - What is XvMC and how does / will that help with the processing > requirements of HDTV playback? Are there particular video cards this > will / will not work with? Anyone have real world examples of > processing improvements (e.g., CPU usage) with XvMC and without? > > And a general question: > > - Is there a way to tell within mythtv what format the ATSC is being > broadcast (720p, 1081i, etc.)? > > Wish I had more answers than questions, but as I get up the learning > curve (and I receive my new, faster CPU), I should be able to > contribute some real-world experience with my HD-3000 (and PVR-250 if > I can ever get them working together). > > Thanks, > Paul > -- > I hear and I forget. I see and I remember. I do and I understand. -- > Confucius >
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